Being underweight can lead to several serious health implications, including a weakened immune system, increased risk of nutritional deficiencies, and potential complications in bone health such as osteoporosis. Individuals may also experience decreased muscle mass, fatigue, and overall decreased energy levels. Mental health can be affected as well, with higher rates of anxiety and depression seen in underweight individuals. Addressing being underweight may require nutritional interventions to ensure adequate caloric intake and a balanced diet aimed at promoting healthy weight gain.